Adjustable ultra high frequency oscillator



May 10,1938. G. L. GRUNDMANN 2,117,090

ADJUSTABLE ULTRA HIGH FREQUENCY OSCILLATOR Filed Feb. 19, 1937 13 1 a 17 flas it 19 9 I :5 11

lmnentor Gustave L.Grurv.dm/anm zoo 15 0 180 v a o I Cttome WAVELENGTH (CM. g

nn'r/o vi /d x 100 Patented May 10, 1938 ADJUSTABLE ULTRA HIGH FREQUENCY OSCILLATOR Gustave L. Grundmann, Westmont, N. J assignor to Radio Corporation of America, a corporation of Delaware Application February 19, 1937, Serial No. 126,565

4 Claims. (01. 250-36) My invention relates to adjustable ultra high frequency oscillators. More specifically, my invention is an adjustable high frequency oscillator in which the tuned. circuit is comprised of an adseciated contact members 23, 25 are moved transverse to the base plate by means of a screw member 2?. The screw member is rotatably anchored to the ground plate 2! by riveting over the end justable transmission line combined with means of the screw member as indicated by reference 5 which provide optimum. output simultaneously numeral 29. The rivet head and the end of the with the adjustment of frequency. I am aware threaded rod 27 are so shaped that bearing shoulthat ultra high frequency oscillators have been ders are formed which permit the screw 21 to be made which employ transmission lines to deterrotated within the threaded portion of the shaft 0 mine the frequency of oscillation. As the fre- 3|. As the shaft 3| is turned in one direction quency increases such oscillators become less efllthe grounding member 2| is drawn toward the cient and require manual control of the feedback base plate I. As the shaft 3| is turned in the which causes the oscillation. Such manual conopposite direction, the grounding member 2| is trol is inconvenient when the oscillator frequency thrust away from the base plate I. This move- 5 must be changed relatively quickly over a subment respectively increases and decreases the stantial range of frequencies. length of the transmission line comprised of One of the objects of my invention is to promembers 3 and 5 to thereby increase or decrease vide an ultra high frequency oscillator with the wave length of the oscillator. means for simultaneously varying the oscillatory The S t 31 has Secured to t by means Of a frequency and the feedback which maintains the y 33 a gear e gear 35 DYOVideS 1 oscillation. ders which engage the base plate I and an auxil- Another object of my invention is to provide iary member 37 which iS suitably secured t0 the means for maintaining ultra high frequency oscilbase p ate- Thlls, the gear 35 being a d 0n lations over a greater frequency range than has one by the base i and on the other side by the been heretofore possible. member 3'! prevents motion of the shaft 3| trans- An additional object is to provide a small portverse to the base plate I as the shaft is rotated. able adjustable oscillator which may be used for At the same time the gear 35 engages a pair of frequency measurements and the like at relagears 39, 4|. Each of the gears 39, 4| includes tively high levels of efficiency. pins 43. The purpose of these pins is to engage One embodiment of my invention is disclosed the threaded portion 1 of the transmission line in Fig. 1 of the accompanying drawing, rods 3, 5. It Will be seen that a movement of the In Fig. 2 a graph illustrates the optimum relacauses movements of the gears 38 and 4|. tion between ground and the point of connecting The pins 43, bearing on the threaded portions 1, the vacuum tube oscillators to the transmission thrust the rods 3, if in a direction transverse to line as a function of wave length, and the base plate I as the gears 39, 4| are rotated. 35

Fig. 3 illustrates a conductor with a non-linear AS the grounding plate is moved back and screw thread employed in a modification of my forth, the rods 3, 5 are likewise moved back and invention. forth so that the total length of the rods 3, 5 is Referring to Fig. l, on a suitable base plate I equal to approximately one-quarter of the wave are arranged a pair of transmission lines 3, 5. length of the oscillatory currents. A pair of vac- 40 The transmission conductors are preferably made uum tubes operated as push-pull oscillators of round rods of low ohmic resistance. One end are connected to the ends of the sleeves 9, I near of each rod is threaded as indicated by the refthe end remote from the base plate I. The pushence numeral 1. The rods are slidably mounted pull circuit connections of the oscillators 45 have in sleeves 9, ll which are secured by brazing, been shown but since the circuits themselves are 45 soldering or the like to the base plate i. Rotanot part of my invention and are well known to tional movement of the rods is prevented by keys those skilled in the art, no detailed description 3, l5 which are secured to rods ii and is necessary. It will, however, be observed that are moved within retaining slots IS. the feedback connection from the push-pull oscil- A grounding plate 2| has mounted therein a lators is caused by that portion of the transmispair of slidable contact members 23, 25 which are sion line which is common to the vacuum tube positioned over the sleeves 9, The contact circuits and the wave length determining rods members are secured to the grounding plate or 3, 5. This common portion is indicated by the member 2| by brazing, soldering or other mereference number d2. That portion of the rod chanical means. The grounding plate and as- 3, 5 which is not common is indicated by the reference number 611. The wave lengtn as previously described is substantially equal to four times the sum of 122 and d1.

Inasmuch as the optimum feedback ratio may be determined for any given oscillator, it will be apparent to those skilled in the art that I have provided means in the gear ratios M and the pitch of threaded portions l, l and 2?, whereby the optimum ratio of to air may be automatically and simultaneously controlled with adjustment of the wave length or frequency of the oscillator. In one such mechanism, I have employed rods which are substantially .8 centimeter in diameter spaced 2.7 centimeters between centers. A pair of so-called acorn tubes, RCA Radiotron Type 955, were used in accordance with the manufacturers rating as to applied voltages and were connected in push-pull as illustrated in Fig. 1.

Using the foregoing tuning device, tubes and circuit connections, the ratio of dz to (ii for an oscillator covering from approximately centimeters to 23:) centimeters Wave length was determined. This characteristic graph is shown in Fig. 2. It wil. be seen that the region from "5 centimeters to centimeters indicates a ratio of 25% to 35%. This ratio would indicate that the screw threads '5 toget er with the gear ratios should produce a ll0ll-l form motion of the grounding plate M with respect to the terminals of the oscillators Whil screw thread may be employed to produce non'uniform motion and may be used in the most refined embodiment of my invention, I have found that over the range in question a uniform 25% ratio of d2 to (11 produces approximately optimum output. If the device is used over a wider wave length range, for example, from 60 centimeters to centimeters, both an increasing and a decreasing pitch for the screw threads "f is indicated. should be understood that the construction which I have shown permits the use of such variable thread, but I prefer to narrow the frequency range and employ a uniform ratio of da to d1 which most nearly conforms to the required ratio.

Thus, I have provided. an ultra high frequency oscillator whose frequency determined by a variable transmission line whose length is automatically adjusted to vary the frequency over a substantial range. Simultaneously with the adjustment of the frequency or wave length, I vary the common or feedback portion of the oscillator circuits and the frequency determining elements to maintain substantially optimum output. It will be observed that the device I have described does not require any insulated bushings and thereby avoids the losses which take place in such insulation when it is used in a high frequency field. By virtue of the simultaneous frequency and feedback adjustment, the oscillator I have described covers a wider range of frequency more efiiciently than has been realized in devices of this type.

I claim as my invention:

1. An oscillator adjustable over a range of high radio frequencies including in combination, an adjustable wave length determining transmission line, a vacuum tube, adjustable connections from said tube to a portion of said line to establish oscillatory currents in said tube, and means for simultaneously varying the effective length of said line and the said connections for establishing oscillatory currents whereby substantially optimum output is obtained from said oscillator over its frequency range.

2. An oscillator adjustable over a range of high radio frequencies including in combination, an adjustable wave length determining transmission line, a vacuum tube, adjustable connections from said tube to a portion of said line to establish oscillatory currents in said tube, means for simultaneously linearly varying the edective length of said line and the said connections for establishing oscillatory currents whereby substantially optimum output is obtained from said oscillator over its frequency range.

3. An oscillator adjustable over a range of high r dio frequencies including in combination, an adjustable wave length determining transmission line, a vacuum tube, adjustable connections from said tube to a portion of said line to establish oscillatory currents in said tube, and means for simultaneously non-linearly varying the effective length of said line and the said connections for establishing oscillatory currents whereby substantially optimum output is obtained from said oscillator over its frequency range.

4. In a device of the character described, an adjustable frequency determining unit, including a pair of conductors, means for simultaneously adjusting the effective length of said conductors, a vacuum tube oscillator having a feedback circuit which has at least a portion common to said conductors, means coupled to said means for adjusting the length of said conductors for simultaneously adjusting the length of said common portion to thereby maintain substantially optimum feedback coupling as said frequency is varied.

GUSTAVE L. GRUNDMANN.

Patented May 10, 1938 BRAZED ARTICLE Horace F. Silliman, Waterbury, Conn, assignor to The American Brass Company, Waterbury, Conn., a corporation oi Connecticut No Drawing. Application February 21, 1936,

Serial No. 65,063

11 Claims. (Cl. 148-21.2)

My invention relates to articles made. by braz- When these alloys contain 3% to 10% tin, they ing, and more particularly to articles, the princican be produced in all wrought forms, such as pal parts of which are formed from a heat hardsheet, strip, rod, wire, tubes, profiles and the like. enable, copper-base alloy and ,joined by brazing With the tin content between 10% and 20% the 5 in a neutral or reducing atmosphere without a alloys are not as suitable for commercial rolling brazing flux. and drawing, but they make desirable castings The object of. my invention is to provide a particularly where good wear resistance and good 1 brazed article having a high corrosion resistance,' bearing p op are required.

high strength and good spring qualities. I have discovered that this alloy not only can The term brazing a u ed in thi specification be hardened and its tensile strength increased (to 10 is understood to mean a form of joining, in which and above 100.000 pounds per qua inch) y a metal or alloy called soldenis caused to melt, heat treatment but that i n l e hydro en then solidify, in' h ner as t n t brazed or brazed in a neutral or reducing atmostallic urfa e phere without the use of a brazing flux. There- Many articles with brazed joints are made comfore fabricated articles may be made y ra 15 mercially but all of these have certain disadvan together wo r r p s mad of thi l y. tages which are not found in the article which I one more parts made of this alloy y be have invented. For example,steel articles brazed brazed to Parts p ed of other metals, and with copper or with copper alloys have high then after the brazing operation the article may strength and good spring qualities but they rus be heat treated to harden the parts made of this 20 wh exposed t moist atmosphere Further.. alloy. As it can be brazed without the use of a more, they dissolve rapidly when exposed to dilute flux the usual disadvantages the presence of id st it elf has a poor resistance to residual brazing flux in the finished article are rosion. The articles made by brazing steel parts eliminatedare even more susceptible to attack by corrosive This alloy can be used either as a solder to 25 agents because at the contact of the steel with the join metal Parts Of higher t ng points, as steel, copper alloy brazing solder in the presence of or Steel and P e of a coppe a e alloy moisture or aqueous solutions, there is formed an of a higher me ting point than this alloy; or it electrolytic cell which greatly accelerates the discan be used COmDOSe Da f the article which integration of the steel. are joined by a 10We1 melting point solder, as

Aluminum aMd magnesium base alloys have a hard solder, etc., and in each case the hydrogen better resistance to atmospheric corrosion but brazing or ng in a neutral or du atthey will not withstand the attack of even Very b p re may be done without the use of a brazslightly acid orvery slightly alkaline agents. mg

:l5 Also they are very weak and they have no qualiother compound tal a s y be formed ties which make them suitable as a material for in a Similar manner- For example, I y 'BZ springs together 1n the manner described a bar of the Articles formed from copper and the copper copper'nickel-tin alloy d bar of a oy alloys brass, bronze, and nickel silver have a with a low coefiicient of thermal expansion like 40 satisfactory corrosion resistance but after being the nickel-iron allbylmown as Invar and roll heated to the brazing temperature they are but the pound bar into a form suitable for use little stronger than the best of the aluminum as a fl in a ermostat. I am not howanoys' I ever confined to the use of Invar but may use I have found that all of these difficulties can other suitable metals. y be. overcome by making the article from one of a Some articles will be improved if the alloy is 40 p i l ser es of pp alloys, brazing the parts modified by the substitution of one or more additogether Wi ut a f u in an atmosphere tional metals for a part of the copper. For exhydrogen or of any suitab e neutral reducing ample, when an article is formed with cutting gas'or mixture of neutral and reducing and tools, that is to say, by machining, the inclusion subjecting the article toacertain heat treatment. 1% of lead improves the Cutting qualities of s The alloys suitable for this purpose comprise: the alloy.

Tin 3 to 20% The elements which may be added to the cop- Nicke1 3.5 to 40% per-nickel-tin alloy in quantities up to 5% of one 5 Copper Balance element and not over 10% of two or more combiped to produce desirable small variations in properties comprise manganese, iron, cobalt, zinc, cadmium, silver, gold, platinum, lead, tantalum, tungsten and arsenic. Certain elements interfere with the brazing operation and must be excluded from the alloy except in very small amounts. These are aluminum, silicon, beryllium, magnesium, phosphorus, titanium, vanadium and chromium.

In fabricating my article I first assemble the part or assembly of parts in the relative position they are to occupy in the finished product, employing, if necessary, a suitable holder, jig or fixture. The space left between the metal surfaces to be joined usually will be about 0.002 to 0.004 inch. The brazing solder in some convenient form, such as wire, sheet, strip, tube, granules, paste or powder is laid adjacent to or in the joint in such a manner that it will not be dislodged during the subsequent handling.

Many copper-base and silver-base solders are suitable for use in making my article. I may employ any of the so-called hard solders which has a flow point below the melting point of the copper-nickel-tin alloy and which is available in the form required for the particular article being made.

With the parts in their proper position and the solder in place, I then put the whole assembly into a furnace in which the air atmosphere has been replaced by hydrogen or by some neutral or reducing gas or mixture of neutral or reducing gases, andheat it to the flow point of the solder.

If, during the assembling operation, the solder has been placed so as to fill the narrow space between the metallic surfaces to be joined, it remains there as it melts and partially alloys with the surfaces. Sometimes, however, it is inconvenient to fill the space with solid solder as the article is assembled. In this case sufficient solder is placed adjacent to the joint so that when it melts it willflow and by capillary action be drawn into the said space. Thus, whether the solder is put'into the joint or adjacent to the joint the action and its effect will be similar.

If my article is not quenched from approximately 600 C. to 850 C. before the hardening heat treatment at 200 C. to 550" C., it does not develop the best possible strength and spring properties. At times, however, it is not convenient to quench the article from the proper temperature as it cools from the brazing temperature. Therefore I may cool the article from the brazing temperature in any convenient way and subsequently reheat it for a period of time up to several hours at 6009.9. to 850 C. and quench in water, oil, molten salt or any other convenient liquid Or in an air blast.

After having brazed the article in the manner described above, I may subject it to a heat treatment which develops the high strength and spring properties. This heat treatment consists of heating the article for a predetermined period of time at a predetermined temperature. The temperature lies within the range approximately 200 C. to 550 C. but the period of time varies considerably. The exact time and temperature of the heat treatment for any specific article is governed by the composition of the alloy from which it is made and the properties desired. For an article made from the alloy comprising tin 7.5%. nickel 7.5%, and copper, a heat treatment of four hours at 350 C. is one of the best. For example,

A heat treatment of one hour at 375 C. gives practically the same results.

As the result of an exhaustive series of tests I have found that certain elements interfere with the brazing operation. These elements seem to react with traces of impurities in the neutral or reducing gas atmosphere and allow the formation of a thin film over the surface of the alloy. This film prevents the solder from wetting the alloy so that joints cannot be made. The elements which act in this manner are aluminum, beryllium, magnesium, silicon, phosphorus, titanium, vanadium and chromium, and therefore if any of these elements is present in appreciable amount the metal parts cannot be brazed in the manner described.

Another series of elements do not have the film-forming characteristic under the conditions under which I braze my article. These comprise copper, zinc, cadmium, iron, cobalt, nickel, manganese, gold, silver, platinum, lead, tin, tantalum, tungsten and arsenic.

I consider it within the scope of my invention to make one or more parts of my article from the heat-hardenable copper-nickel-tin alloy and other parts from any alloy composed only of elements selected from the series mentioned above, namely copper, Zinc, cadmium, iron, cobalt, nickel, manganese, gold, silver, platinum, tin, lead, tantalum, tungsten and arsenic. Thus I may form certain spring parts of an article from the copper-nickel-tin alloy but in order to reduce the cost of material I could use brass, a copper-zinc alloy, for other parts which were not to be flexed.

One of the applications where my invention is of especial value is in the production of base metal sheet, rod, wire, tubes, and other desirable shapes coated with noble metals such as gold, silver, tantalum or platinum or their alloys. The alloys ordinarily used as base metals such as brass,

bronze, and nickel sil'ver are not strong enough for many purposes. High strength alloys like beryllium-copper, copper-nickel-aluminum-zinc, copper-nickel-silicon, and copper-cobalt-silicon cannot be joined to gold, silver, platinum and their alloys by brazing or silver soldering in reducing or neutral gases without a flux because the solders will not wet them and therefore will not flow. If a flux is used to dissolve and remove the film of oxide which prevents the flow of the solder this flux cannot be entirely removed from between the layer of base metal and noble metal and is apt to produce blisters which give trouble during subsequent rolling, drawing, blanking and other forming operations.

Under my invention the copper-nickel-tin alloy and the noble metal may be clamped together with a thin layer of brazing solder between them without flux, heated in a neutral or reducing atmosphere and cooled as described above. This bimetal sheet, rod, wire, tube, or whatever form it may be, is then rolled, drawn, blanked, formed,

pressed and worked in any other manner until it assumes the desired shape. After all the shaping operations are completed. the article may if desired be brazed again with a solder having a lower melting point than that used to join the copper-nickel-tin alloy and the noble metal and without a flux, after which it is heat treated to develop the required mechanical properties.

Another example of the article which I have invented is a metal bellows. This bellows is made by brazing together sheet metal sections. A bellows of this type which is satisfactory from the mechanical standpoint can be made from steel sheet by brazing, but when used in contact with water and aqueous liquors, steel rusts very rapidly. Making the bellows from copper base alloys prevents rust. However, all copper alloys, except those comprising copper, nickel and tin (in the absence of aluminum, silicon, beryllium, magnesium, phosphorus, titanium, vanadium and chromium) are objectionable either because they lack the necessary spring qualities after brazing or because they cannot be brazed without a flux. In this application it is essential that the use of a flux be avoided because even the slightest discontinuity resulting from residual flux allows leakage of the gas or liquid which the bellows contains and thus renders it useless for its intended purpose. Furthermore, the excess flux which adheres to the inside surfaces of the bellows cannot be removed after the bellows is brazed and soon causes pitting especially when it contains hygroscopic compounds.

The examples given above serve merely to show the essential features of my article and they should not be considered the only articles within the scope of this invention. The appended claims should be construed to cover any corrosion-reslsting article which is formed from the alloys mentioned joined by brazing or silver soldering in an atmosphere of reducing or neutral gas or mixture of gases and may have high strength and good spring properties imparted to it by the heat treatment described.

Having thus set forth the nature of my invention, what I claim is:

1. A brazed article comprising a plurality of metal parts of which at least one of said parts is composed of a copper base alloy comprising 3% to 20% tin, 3.5% to 40% nickel and balance substantially copper, said alloy being characterized by being hardenable by heat treatment, and said parts having been Joined together by brazing without flux in a neutral or reducing atmosphere whereby the brazed joint is free of flux.

2. A brazed article comprising a plurality of metal parts composed of an alloy comprising 3% to 20% tin, 3.5% to 40% nickel, and balance substantially copper, and said parts having been joined together by brazing without flux in hydrogen or other suitable neutral or reducing gas or gas mixture so that the brazed joint is free of flux.

3. A brazed article comprising a plurality of metal parts composed of an alloy comprising 3% to 20% tin, 3.5% to 40% nickel, and balance substantially copper, said parts having been joined together by brazing without flux in a reducing or neutral atmosphere so that the brazed joint is free of flux, and said alloy having been cooled quickly from a temperature just below the i'reezing point of the brazing solder and strengthened by reheating at a temperature within the range 200' C. to 500 C.

4. A brazed article comprising a plurality of metal parts composed of an alloy comprising 8% to 20% tin, 3.5% to 40% nickel and balance substantially copper, said parts having been joined together by brazing or hard soldering in a neutral or reducing atmosphere without ilux so that the joint is free of i'iux, and to which article spring qualities have been imparted by heat treatment.

5. A brazed article comprising a plurality of metal parts composed of a heat hardened copper base alloy comprising 3% to 20% tin, 3.5% to 40% nickel and balance substantially copper, and said parts being joined by one or more brazed joints which were made by heating in a neutral or reducing atmosphere without flux so that the joint or joints are free of flux.

6. A brazed article comprising a plurality of parts joined together by brazing in a neutral or reducing atmosphere without flux so that the joint is free of flux, said parts being composed of a copper base alloy comprising 3% to 20% tin, 3.5% to 40% nickel and balance substantially copper which is characterized by being corrosion resistant and hardenable by heat treatment.

7. A'brazed flexible metal bellows comprising a plurality of heat hardened metal parts composed of a copper base alloy comprising 3% to 20% tin, 3.5% to 40% nickel and balance substantially copper, and which parts were joined by brazing without flux by application of heat while in an atmosphere of hydrogen or other suitable reducing or neutral gas or gas mixture so that the joints are free of flux.

8. A brazed flexible metal bellows comprising sheet metal sections composed of an alloy of 3% to 20% tin, 3.5% to 40% nickel and balance substantially copper, which are brazed together without flux in a neutral or reducing atmosphere so that the brazed joints are free of flux, and said plates being cooled quickly from a temperature of 600 C. to 850 C. and strengthened by reheating at a temperature within the range 200 C. to 500 C.

9. A method of making a brazed article comprising brazing together in a neutral or reducing atmosphere without flux a plurality of parts at least one of which is composed of a worked, heat hardenable alloy comprising 3% to 10% tin, 3.5% to 40% nickel, and balance substantially copper, so that the brazed joint is free of flux.

10. A method of making a flexible bellows comprising brazing together in a neutral or reducing atmosphere without flux a plurality of parts composed of a worked alloy comprising 3% to 10% tin, 3.5% to 40% nickel and balance substantially copper, cooling quickly from a temperature of 600 C. to 850 C. and maintaining at a temperature of 200 C. to 550 C. for a suihcieht time to produce a material increase in hardness.

11. A method of making a flexible metal bellows comprising brazing together a plurality of flexible parts by heating in a neutral or reducing atmosphere without flux so that the brazed joint is free of flux, said parts being composed of is worked alloy comprising 3% to 10% tin, 3.5% to 40% nickel and balance substantially copper.

HORACE F. SILLIMAN. 

